1. (a) Field of the Invention
This invention relates to a method for manufacturing a molding with brightening property, to be mounted on the periphery of a window pane, at the front, rear or side part of the body of vehicles, in particular, automotive vehicles.
2. (b) Description of Prior Art
The molding to be mounted on the periphery of the window pane of an automobile, for example, is difficult to be manufactured in a continuous length and, even if possible, manufacturing of such molding would, inevitably, increase production cost. Because of this, it has been the practice, in the case of manufacturing a molding to be mounted on and around the window pane of a 4-door type sedan M as shown in FIG. 8 of the accompanying drawing to this application, to manufacture the front door molding assembling a rectilinear front door molding A, a front sash molding B having a slightly curved portion and rectilinear portions connected before and after the curved portion, with a front corner C for joining the moldings A and B. The rear door molding is manufactured by assembling a rectilinear rear door molding D, a rear sash molding E, and a rear pillar molding F, with corner parts, at both ends, thereof, joining each of the moldings D and E.
In order to obtain the corrosion-resistant property and the brightening property, the abovementioned door molding A, the front sash molding B, the rear door molding D and the rear sash molding E are produced by first roll-forming stainless steel web into the main body for the molding having a required cross-sectional shape, then passing the thus shaped main body of stainless steel web through an extrusion molding machine to integrally provide an edge part, protruded part and connecting parts of a soft synthetic resin material (usually, vinyl chloride) in the longitudinal direction of the main body of stainless steel web; and, finally, cutting the lengthy main body into pieces of required length.
The front sash molding B is bent by passing such section through a bender. Because the front corner molding C has a small radius of curvature, the rear pillar molding F has different width between its upper part and lower part and its overall configuration is complicated because of corner parts on both upper and lower ends thereof, the main bodies of these component parts cannot be manufactured by roll-forming and bending, alone.
In view of the foregoing, the conventional method of manufacturing component parts for such the molding has been such that the main bodies of the front corner C and the rear pillar molding F are manufactured by die-casting of zinc, or injection-molding of rigid synthetic resin such as ABS resin, and so forth. The thus shaped main bodies are plated with chromium; and, thereafter, the edge part and the protruded part made of a soft synthetic resin, or other elastomeric materials, are attached onto predetermined positions of the main bodies.
Because conventional molding for the vehicles are of such construction as mentioned above, there inevitably takes place a phenomenon such that the component parts of the moldings, as joined together, assume different brightening colors of stainless steel and chromium-plating, from one to the other, due to difference in configuration of the moldings, depending on the position of their attachment onto the vehicle body, which might give delicate difference in color tone, and, hence, unsightly appearance to the viewers, even though such component parts assume the same metallic brightening colors.
With a view to avoiding such unsightliness, there has been practiced a method of treatment, in which the portion of the molding made of stainless steel main body, which is exposed to the outside, is subjected to buffing so as to bring the stainless steel color closer to the chromium color. Even with this treatment, however, there is a limit to adjustment of the color tone. In addition, there is an apprehension such that the shaped part of the soft synthetic resin might be impaired by the machining. Hence, no satisfactory result can be obtained.
As another method, the roll-formed main body of the stainless-steel web is plated with chromium, onto which the edge member and the protruded member of soft synthetic resin, or other elastomeric materials, formed in advance by the extrusion-molding and then cut into a required length, are attached onto predetermined positions of the stainless steel main body with an adhesive agent. This method, however, is still disadvantageous in that not only the adhesion of the edge member, etc. is time-taking and troublesome, but also the edge member and protruded member, as adhered onto the main body of the molding, might become sinuous, or leave a clearance between the main body and the edging member, etc. with the consequence that the molding is in poor finish and the final products are irregular and non-uniform in quality.